This invention relates to a throttle angle sensor sensing a rotation angle of a throttle valve of an internal combustion engine in the form of an electrical signal.
JP-Y2-61-4093l, which was filed as a Japanese utility model application on Dec. 12, 1980 and laid open on Nov. 21, 1986, discloses a throttle angle sensor which includes a potentiometer mounted at one end of the shaft of a throttle valve. In the disclosed throttle angle sensor, a slide terminal or contact slides in response to the rotation of the throttle valve thereby changing the resistance value of the potentiometer. Therefore, unless the throttle valve shaft and the potentiometer are assembled with high accuracy, the throttle angle sensor will be subjected to mechanical damage. Further, the throttle angle sensor has the problem of wear and mal-contact at the slide contact.
A non-contact type throttle angle sensor which solves the problem of the contact type throttle angle sensor described above is disclosed in, for example, JP-A-56-107119 which was filed as a Japanese patent application on Jan. 30, 1980 and laid open on Aug. 25, 1981. Non-contact type throttle angle sensors using a Hall effect element for angle detection ar also disclosed in, for example, JP-A-58-211603 which was filed as a Japanese patent application on June 3, 1982 and laid open on Dec. 9, 1983 and in JP-A-60-140103 which was filed as a Japanese patent application on Dec. 28, 1983 and laid open on Jul. 25, 1985.
In the prior art throttle angle sensors of both the contact type and the non-contact type, high accuracy which minimizes a change in the output relative to a change in the rotation angle of the throttle valve is required together with requirement for minimum adjustment of the input-output characteristic during the manufacturing process and smallest possible man-hours required for the manufacture.